Power distribution network permanent fault identification method based on injected signal

Abstract

The invention discloses a power distribution network permanent fault identification method based on an injected signal. An intelligent load switch provided with an FTU is adopted to take the place of a sectionalizer, and a topological structure of a whole feeder keeps complete and can not be divided into multiple sections after an interphase short-circuit fault and three-phase trip happen on the feeder. Under the background, the power distribution network permanent fault identification method based on the injected signal is disclosed. The method includes the steps that a constant-frequency voltage detection signal is injected between faulty phases after the trip fault of the feeder, an equivalent input impedance of a faulty interphase port is calculated by means of detected voltage and current of the injected signal, and the equivalent input impedance is compared with an equivalent input impedance obtained before the fault and based on a power frequency signal at normalized frequency; amplitudes of the impedances are proximately equal during an instantaneous interphase fault; the amplitudes of the impedances are much different during a permanent fault, a permanent short-circuit fault is identified, and self-adaptation reclosing is further achieved. By means of the scheme, secondary short-circuit current rush caused due to the fact that reclosing is carried out during the permanent fault can be effectively avoided, and power supply of a faulty line can be quickly and conveniently restored.

Description

technical field [0001] The invention relates to a method for identifying a permanent fault of a distribution network, in particular to a method for identifying a permanent fault of a distribution network based on an injected signal. Background technique [0002] At present, the reclosing of the distribution network generally adopts the traditional automatic reclosing method that does not consider the adverse effects of reclosing failure. Most of them are realized by the cooperation of the circuit breaker at the head end of the feeder and the sectionalizer at each branch. After a phase-to-phase short-circuit fault occurs on the feeder, the feeder head-end circuit breaker trips three phases, the entire feeder loses power and loses voltage, each sectionalizer opens, and the head-end circuit breaker recloses after a fixed time delay. Overlapping, the process takes about several minutes to complete, which greatly reduces the power supply reliability of the distribution network. I...

AI Technical Summary

Problems solved by technology

For the distribution network, when a phase-to-phase short-circuit fault occurs and the three-phase trips, the entire line is powered off, and the electrical quantity that reflects the fault information after the trip cannot be obtained. In addition, the distribution feeder has many branches and a complex topology, which is used for the permanent transmission system. The fault identification method cannot be applied to the power distribution system

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